Histogram

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sonata31
Posts: 57
Joined: Wed May 05, 2021 3:51 pm

Histogram

#1

Post by sonata31 »

Hello
In SharpCap the Histogram is displayed like this
Image
How to have a display like this
Image
Thanks for your help
Louis
Monture : Rainbow Astro RST135E
Lunette : Takahashi FSQ106EDX4 + PegasusAstro FocusCube
Alnitak Flip-Flat
Caméra : ZWO ASI533MC + EFW
PC : PrimaLuceLab EAGLE4 PRO
Logiciels : SharpCap, ASTAP, PHD2
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admin
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Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
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Re: Histogram

#2

Post by admin »

Hi Louis,

the top histogram is one from a camera in high bit depth mode (12, 14, 16 bits). That always shows a finer graph than a camera in 8 bit mode (which is the style of the bottom histogram).

Also, your camera running in high bit depth mode is producing data that has missing values - that is some brightness values are being used and others are not (over and above the fact that a camera with a 12 bit sensor will only give values of 0, 16, 32, 48, 64, etc when using 16 bit output). This causes the white painted nature of the histogram and also all the individual spikes in the red/green/blue data that you can see behind the white.

The usual caus of this sort of problem is using some of the image processing controls of the camera - typically one or more of contrast, gamma, white balance red/green/blue. If you set these controls back to their default values then your histogram should return to normal.

thanks,

Robin
sonata31
Posts: 57
Joined: Wed May 05, 2021 3:51 pm

Re: Histogram

#3

Post by sonata31 »

Hello
The top histogram is that of the image of the "Test Camera 1 (DeepSky)"
Louis
Monture : Rainbow Astro RST135E
Lunette : Takahashi FSQ106EDX4 + PegasusAstro FocusCube
Alnitak Flip-Flat
Caméra : ZWO ASI533MC + EFW
PC : PrimaLuceLab EAGLE4 PRO
Logiciels : SharpCap, ASTAP, PHD2
User avatar
admin
Site Admin
Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Histogram

#4

Post by admin »

Hi,

in that case the white fill in the foreground is either being caused by gaps in the histogram of the image you are loading *or* from the gamma/gain control settings in the camera controls. You also have set the test camera to use 16 bit data (RAW16), so you could set that back to RAW8 or RGB32 if you wanted.

hope this helps,

Robin
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